In the first episode of the second season, "Two Princesses and a Baby", Rex plays a more active role, and speaks for the first time. He steals Cedric's spell book and buries it for everyone to find it. It turns out that Rex loves to play games and like all dogs, he loves to bury bones. He is a bit goofy, but he claims he is smarter than he looks. Rex is also shown to be a bit forgetful. When Rex buries Cedric's spell book in "Two Princesses and a Baby" he forgets which hole he buried it in. As a result, Clover and his friends come up with a plan in order to find the location of the spell book.

In "When You Wish Upon a Well", he chases after Sofia when she becomes a cat. Sofia eventually manages to get away from him, and James puts him back on his leash.

Trivia

As he stated in "When You Wish Upon a Well", he does not listen to anyone but his master. He does not even listen to Clover in "Clover Time" while cannonballing in Sofia's bed during the "party".